Hydronephrosis and Hydroureter Treatment & Management

The role of medical treatment of hydronephrosis and hydroureter in adult is limited to pain control and treatment or prevention of infection. Most conditions require either minimally invasive or open surgical treatment. Two notable exceptions are (1) oral alkalinization therapy for uric acid stones and (2) steroid therapy for retroperitoneal fibrosis.

The management approach of infants with antenatal hydronephrosis is based on the confirmation of persistent postnatal hydronephrosis and the following 2 predicative factors.

• Bilateral involvement
• Severe hydronephrosis: Fetuses with a renal pelvic diameter greater than 15 mm during the third trimester are at the greatest risk for significant renal disease.

Bilateral hydronephrosis

Infants with severe bilateral antenatal hydronephrosis and/or bladder distension are at increased likelihood of having significant disease. These infants and those with a severe hydronephrotic solitary kidney should be evaluated initially by ultrasonography on the first postnatal day. Bilateral hydronephrosis suggests an obstructive process at the level or distal to the bladder, such as ureterocele or posterior urethral valves (PUV) in a male infant, which can be associated with impaired renal function and ongoing renal injury.

If postnatal ultrasonography demonstrates persistent hydronephrosis, voiding cystourethrography (VCUG) should be performed. In male infants, the posterior urethra should be fully evaluated to detect possible PUVs.

Infants with mild or moderate hydronephrosis can be evaluated after 7 days of life.

Severe unilateral hydronephrosis

In newborns with severe antenatal unilateral hydronephrosis (renal pelvic diameter >15 mm in the third trimester), ultrasonography should be performed after the infant returns to birth weight (after age 48 h and within the first 2 wk of life).

Moderate and mild unilateral hydronephrosis

In newborns with less severe antenatal unilateral hydronephrosis (renal pelvic diameter < 15 mm during third trimester), ultrasonography can be performed after they reach age 7 days see if the hydronephrosis is persistent postnatally.

Most patients with moderate hydronephrosis have resolution by age 18 months.^[25] This was illustrated by a prospective study of 282 infants (age 2 mo) with renal pelvic diameters between 10 and 15 mm, which resolved (defined as renal pelvic diameter ≤5 mm on 2 consecutive ultrasounds) in 94% of patients by age 12-14 months. Of the 18 patients with persistent hydronephrosis, 14 had ureteropelvic junction (UPJ) obstruction and 4 had vesicoureteral reflux (VUR).

Antibiotic prophylaxis

Higher rates of urinary tract infections have been reported in children with prenatally diagnosed hydronephrosis compared with the general pediatric population.^{[26, 27]} The risk of infection rises if there is an underlying urologic abnormality, such as VUR or obstructive uropathy, and is greater in girls compared with boys.^[28]

As a result, in infants with severe hydronephrosis who are at greater risk for an underlying urologic abnormality, antibiotic prophylaxis is started after delivery until the diagnosis of VUR or obstructive uropathy is excluded.

Antibiotic prophylaxis in children with mild or moderate hydronephrosis confirmed postnatally has not been studied prospectively. In one retrospective study of 1514 with mild persistent hydronephrosis, the use of prophylactic antibiotics reduced the risk of febrile urinary tract infection in patients who had VUR.^[29] Until further prospective studies are conducted, antibiotic prophylaxis should be considered until VCUG has been performed and either the diagnosis of VUR has been made or eliminated.

Antibiotic prophylaxis is not needed in infants with normal postnatal ultrasonography findings.^[30]

The specific treatment of a patient with hydronephrosis and hydroureter depends, of course, on the etiology of the process. Several factors help determine the urgency with which treatment should be initiated. In general, any signs of infection within the obstructed system warrant urgent intervention because infection with hydronephrosis may progress rapidly to sepsis. A mildly elevated white blood cell count is often observed in patients with stones but does not necessarily mandate immediate action in the absence of other signs or symptoms of systemic infection. However, even a low-grade fever in a diabetic or immunosuppressed patient (ie, on steroid therapy) requires immediate treatment.

The potential for loss of renal function also adds to the urgency (eg, hydronephrosis or hydroureter bilaterally or in a solitary kidney). Finally, patient symptoms help determine the urgency with which treatment is initiated. For example, refractory pain in a patient with an obstructing ureteral calculus necessitates intervention, as does intractable nausea and vomiting.

Urethral catheterization is important to help rule out a lower tract cause for hydronephrosis and hydroureter. Difficulty in placing a Foley catheter may suggest urethral stricture or bladder neck contracture.

Urologists commonly use ureteral stent placement in cases of intrinsic and extrinsic causes of hydronephrosis. The procedure is usually performed in conjunction with cystoscopy and retrograde pyelography. Stents can bypass an obstruction and dilate the ureter for subsequent endoscopic treatment.

Urologists or interventional radiologists can place a percutaneous nephrostomy tube if ureteral stenting is not possible. Usually, ultrasonography is used first to locate the dilated collecting system. Using the Seldinger technique, a tube ranging from 8-12F can be placed. Nephrostomies are typically placed when a retrograde stent cannot be passed because of anatomic changes in the bladder or high-grade obstruction in the ureter. Because this procedure can be performed under local anesthesia, patients who are too hemodynamically unstable for general anesthesia may undergo percutaneous nephrostomy tube placement. In addition, nephrostomy tube placement may be performed with minimal use of radiation and may be useful in pregnant patients.

Advances in endoscopic and percutaneous instrumentation have decreased the role of open or laparoscopic surgery for hydronephrosis. Certain causes of hydronephrosis, mostly extrinsic, still require treatment with open surgery. Examples include retroperitoneal fibrosis, retroperitoneal tumors, and aortic aneurysms. Some stones that cannot be treated endoscopically or with extracorporeal shockwave lithotripsy require open removal. Although endoscopic management does play a role in low-grade low-stage ureteral tumors, these lesions also usually require open or laparoscopic surgical management.

Urine should be collected from the kidney when obstruction is relieved to allow identification and targeted treatment of any infection that may be present.

Fetal surgery

Although several prospective and retrospective studies have examined antenatal surgery in fetuses with sonographic findings consistent with lower urinary tract obstruction, no good evidence supports that this intervention improves renal outcome.^[31] The rate of chronic renal disease is high in the survivors, necessitating renal replacement therapy in almost two thirds of the cases. These procedures may increase the amount of amniotic fluid, thus potentially improving lung development and survival rate; however, further studies are needed to determine whether intervention improves survival.

Antenatal surgery should only be performed in select centers with expertise. Currently, a clinical trial comparing conservative management without surgical intervention to vesicoamniotic shunting in singleton fetuses younger than 28 weeks’ gestation with isolated bladder outflow obstruction is recruiting sites and patients.^[32] The hope is that results of this trial will answer whether surgical intervention improves clinical outcome.

Refer the patient to a urologist whenever hydronephrosis or hydroureter is newly diagnosed. Further consultations may be sought by the urologist, depending on the circumstances. For example, a nephrologist's input would be useful in cases of severe pathological postobstructive diuresis. In addition, an interventional radiologist would be needed for nephrostomy tube placement if urgent decompression is needed and ureteral stent placement is not possible. Patients with antenatal and postnatal hydronephrosis should be referred to a pediatric urologist for evaluation and management.